Adam
So far the only response I have had to my questions on this is an email from Boris to the effect they are looking into this, that was 3 months ago, so in the fullness of time there may be a fix.
It is interesting to note all the new products Boris are putting out Edius is not mentioned in the Advertising, it looks like they have dropped Edius
The only way is to use Boris outside Edius for any active filter which precludes Transitions.
As a suggestion try Vitascene from Prodad works well and is not render intensive
Regards Barry